Artificial leg having a lockable knee joint responsive to foot pivoting and body weight



July 8, 1969 o. MINOR 3,453,663

ARTIFICIAL LEG HAVING A LOCKABLE KNEE JOINT RESPONSIVE T0 FOOT PIVOTINGAND BODY WEIGHT Filed April 20, 1967 Sheet. I of 2 FIG 2 I I :4 l "I 8 II 9/ J l -4- i a; 27

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United States Patent US. Cl. 3--23 Claims ABSTRACT OF THE DISCLOSURE Anartificial leg incorporating a pivotal knee joint actuated from amovable ankle joint. The knee joint of this prosthetic device is lockedby limited pivoting of the ankle joint and placement of body weight uponthe knee joint. In this manner the knee joint is prevented fromcollapsing under any conditions wherein body weight is applieddownwardly upon the limb, or leg; and not only does the particular kneejoint control hereof readily accommodate the normal motions of walking,but also automatically locks upon body-weight shifting, such as mightoccur at the commencement of a fall or stumble, so that the leg cannotcollapse under the person wearing same. Additionally, the presentinvention provides a cushioning effect in the locking of the joint whileat the same time allowing a free lower-leg pivoting upon the removal ofbody weight from the leg.

The present application is a continuation-in-part of my prior copendingpatent application Ser. No. 397,862, filed in the US. Patent Office onSept. 21, 1964, and entitled, Artifical Limb, now abandoned.

Background of invention Since the early days of the solid, woodenartifical limbs, there have been many notable improvements made injointed limbs. In particular, since the World War II, there have beendeveloped artificial limbs which in many ways approximate the jointmovements of natural limbs. There are yet, however, many limitations inconventional artificial limbs which prove exceedingly trying to thoseutilizing them.

More specifically with regard to artificial legs, including knee andankle joints, it is conventional for the knee joint to lock with theupperand lowerleg portions in alignment. This locking is normallynecessary to prevent collapse of the leg when weight is placed thereon.During walking, the lower leg is normally moved forwardly by a freeswing. With theleg joint unlocked, the upper leg is moved forward tothereby impart a pivotal motion to the lower leg which swings in a freearc into alignment with the forwardly-extended upper-leg portion andthereupon locks therewith, so that weight may be placed upon theoutstretched leg. While this operation is highly advantageous over anonjoined leg, it does provide somewhat of a stiff-legged walk; and,furthermore, fails to accommodate conditions wherein the upperandlowerleg portions should not be in alignment when the body weight isplaced thereon. These latter conditions arise in climbing or walkingalong inclined surfaces, for example. More particularly, a personWalking along the side of a ice bill, for example, normally does notfully extend the leg on the uphill side of the body, i.e., it isnecessary for the two legs to have effectively different lengths to walkunder these conditions. Similarly, climbing of stairs requires lockingthe knee joint with the upperand lower-leg portions inclined withrespect to each other and although certain known artificial legs attemptto accomplish this result, there remains the problem of climbing aninclined surface in which the foot is always inclined with respect tohorizontal. Considerable difficulty is often encountered in negotiatingthis type of surface with a conventional artificial leg.

Although a wide variety of artificial-leg structures are known in theart, certain of these are more relevant to the present invention in thatthey do relate to flexible ankle devices. It is common for these priorart devices to incorporate a substantial degree of complexity while yetbeing limited insofar as full safety for the user is concerned. Some ofthe relevant prior art in this field of prosthetic devices is to befound in US. Patents Nos. 21,289 to Wilcox, 1,685,219 to Neumann,2,575,802 to Fischer et al. and 2,924,828 to Chiasson. Additionally, asubstantial amount of work in this field has been accomplished inforeign countries, as exemplished by Austrian Patent No. 168,889 andGerman Patent No. 347,920.

It is common in jointed artificial limbs for control over the joints tobe provided from the body end, i.e., artificial legs are normallycontrolled as to the knee joint by the upper-leg portion. The presentinvention operates quite oppositely by providing control over the kneejoint from the foot. Careful consideration of the mechanical operationof walking shows that locking, unlocking, and pivoting of the knee jointmay be directly related to the positioning of the foot. The human kneeprovides for looking of the knee joint with the upperand lower-legportions inclined with respect to each other. While the presentinvention does not provide the full equivalent of a human knee joint, itdoes provide for locking of the knee joint, with the upperand lower-legportions inclined with respect to each other and weight placed on thefoot, and the foot is inclined with respect to the lower-leg portion.The present invention also provides for freeing the knee joint whenweight is removed therefrom, so that the lower leg and foot may swingthereabout. These features provide a close approximation of the degreeof motion and limitation of motion present in normal human legmovements.

It is possible for a person wearing an artificial leg in accordance withthe present invention not only to walk along a horizontal surface in anormal manner, but also to walk up or down an inclined surface in anormal manner, walk along a laterally inclined surface in eitherdirection and to place weight on the artificial leg with the knee bent.The invention additionally provides the normal degrees of motionnecessary, such as free swinging lower leg and foot, as required in aseated position. Additionally, the in vention provides positivemechanical stops, or locks, completely eliminating any possibility ofreverse knee joint rotation or knee joint collapse.

Description of figures The present invention is illustrated as to asingle preferred embodiment thereof in the accompanying drawingswherein:

FIGURE 1 is a side-elevational view with a portion of the coveringremoved;

FIGURE 2 is a read-elevational view of the invention with a portion ofthe covering removed;

FIGURE 3 is an enlarged partial-sectional view taken in the plane 33 ofFIGURE 2; and

FIGURE 4 is an enlarged partial-sectional view taken in the plane 4-4 ofFIGURE 2.

Description of preferred embodiment Considering now the illustratedembodiment of the present invention in some detail and referring firstto FIG- URES 1 and 2 of the drawings, it will be seen that the inventionhereof includes an upper-leg portion 21, a lowerleg portion 22, and afoot portion 23. The upper-leg portion 21 is adapted to be connected inany desired manner either directly or preferably indirectly to the legof an amputee, and is joined to the lower-leg portion 22 by a knee joint24. The upper-leg portion 21 may, for example, be provided with a flatupper surface having a key affixed thereacross and adapted forengagement with a keyway in the under surface of an upwardly extendingelement adapted to be directly aflixed to the leg of an amputee withsuitable locking means between the two, so that this upper means may beprovided separately from the device of the present invention. The bottomor lower leg portion 22 is connected to the foot 23 by an ankle joint26, so that the foot is pivotally connected to the leg. No attempt ismade herein to illustrate details of the foot 23, for such does not forma part of the present invention. It is, however, noted that the varietyof different artificial feet is known in the art and commerciallyavailable. The present invention provides for modification of the upperor ankle connection of the foot in the manner described below; and it isnoted that at least limited flexing of the foot at the ball thereof isdesirable.

A suitable outer cover 27 is provided as a shell, or envelope for thelower-leg portion of the present invention, and within this cover aremounted the working parts of the artificial leg hereof. There isadditionally provided an outer cover 28 about the upper-leg portion 21to cover the knee joint; and it will be seen that the covers 27 and 28are formed to accommodate pivoting of the knee joint, i.e., upper-legportion with respect to lower-leg portion, without interference betweenthe covers. The ankle joint 26 is formed by a pair of upstanding sidewalls 29 affixed to the top of the foot 23, and having a transverseankle shaft 31 extending therebetween. These upstanding walls 29 areappropriately curved at front and back surfaces, as indicated, so thatupon forward and backward pivoting of the foot, there will be nointerference between the foot and upstanding walls thereon with thelower-leg cover 27.

Further with regard to the actual structure of the preferred embodiment,it is noted that a pair of rigid and structurally strong side plates 32and 32 are provided in extension between the ankle joint and the kneejoint. The ankle joint itself is provided by extension of the transverseshaft 31 through the side plates 32, 32 in rotary relation thereto, sothat aside from other elements of the invention, the foot is free topivot about the ankle joint in the plane of FIG. 1. In order to conformthe general configuration of a lower-leg, the side plates 32, 32 areeach formed with a vertical bottom portion 33 connected to a verticalupperportion 34 by an outwardly tapered central portion 36. Inasmuch asartificial limbs must normally be provided in a plurality of differentsizes, the present invention is usually lengthened by varying the lengthof the lower vertical portion 33 of the side plates; and, of course,varying the overall length of the cover portion 27 proportionately.Metal bands 35 or the like may be provided to mount the cover 27 thatmay snap thereon.

Considering now the knee joint itself, it is noted that same includes ashort transverse cylinder 41 having end plates 42 affixed thereto andcarrying appropriate attachment means for the upper leg. This cylinder41 is rotatably mounted between the upper ends of the side plates 32,32' as by means of axial stub shafts 43, so that the upper-leg portion21 is free to rotate about the lower-leg portion or vice versa. The kneecylinder 41 has a central V-groove 44 extending about the circumferencethereof, possibly as best illustrated in FIGURE 3. The upperand lowerlegportions are afiixed together in relatively rotatable relationship bymeans of engagement between the cylinder 41 and side plates 32, 32', sothat the knee joint is adapted for pivoting.

Appropriate braking or locking means are provided for the knee joint andoperable from the ankle joint. This feature of the present invention isof particular importance inasmuch as it does provide for locking of theknee joint when weight is placed thereon and pivoting of the ankle jointoccurs. The locking force increases with increasing pivotingof the anklejoint in the manner described below so as to thus exclude any and allpossibility of collapsing of the knee joint during any conceivable typeof usage thereof. The braking or locking means for the knee jointincludes a V-belt 46 disposed within the circumferential groove 44 aboutthe cylinder 41 and extending about a cam 47, pivotally mounted beneaththe knee joint between the side plates 32, 32'. A knurled cylindricalshaft 48 is fixedly mounted between the side plates 32, 32' between theknee joint and cam with the belt 46 lapping partially around such shaftbetween the joint and cam in the manner clearly illustrated in FIGURE 1.Locking of the knee joint 24 is accomplished by tightening of the belt46 thereabout through rotation of the cam 47. To this end the cam 47 isprovided with an eccentric cam surface 49 extending further to one sideof the cam shaft 51 than to the other. The cam is mounted on the camshaft 51 between the side plates 32, 32' for free rotating thereabout.Provision is made for adjusting the cam position and looking it betweenthe belt and shaft by a set screw 52 threaded through an upper extensionof the cam actuator 53, also mounted on the cam shaft and having a pairof arms 54-54 extending rearwardly therefrom. The adjusting screw isadapted to bear against a rear cam surface, as indicated in FIGURES 3and 4. There are also shown to be provided a pair of clamps 56 bolted tothe exterior surface of the cam and extending over the V-belt 46 to holdthe belt against the cam surface. Actuation of the cam is accomplishedfrom the ankle joint as described below.

As shown in FIGURES 1 and 2, there are provided a pair of activators 61and 62 extending from the ankle to the vicinity of the cam 47. Each ofthese activators is similarly constituted to be pivotally mounted atboth ends and adjustable in length. To this end, the activator 61, forexample, may include a central bar 63 threaded into a lower nipple 64having a lock nut 66 threaded on the bar against the top of the nipplewith the nipple pivotally mounted on a transverse anchor pin 67extending between the side plates 29 of the ankle. This particularactivator is mounted with the anchor pin ahead of the ankle shaft 31toward the front of the foot. At the upper end of the activator, the bar63 is threaded into an upper nipple 68 which has a transverse slot 69therethrough and extending longitudinally thereof with a set screw 71threaded into the opposite end of the nipple to extend a predeterminabledistance into the slot for defining the effective slot length. The otheractivator 62 is, as stated above, constituted in the same manner as theactivator 61; however, the transverse anchor pin 67' thereof is mountedbehind the ankle shaft 31, as clearly shown in FIGURE 1. The twoactivators are mounted interiorly of the side plates 32, 32' with one ofthe activators 61 being mounted adjacent the side plate 32' and theother activator 62 being mounted adjacent the side plate 32.

As stated above, the activators 61, 62 operate the cam 47 from the anklejoint to lock the knee joint. This is accomplished by an extension of anactivator pin 81 between the cam actuator arms 54, 54' through the slots69, 69' of the activators 61 and 62. Pivoting of the foot 23 to raisethe front portion thereof will be seen to move the activator 61 upwardlywith respect to the side plate 32' inasmuch as the anchor pin 67 islocated ahead of the ankle shaft 31. This, then causes the activator 61to force the cam actuator 53 to rotate clockwise about the cam shaft 51and thus to swing the cam 47 in a clockwise direction to thereby tightenagainst the belt 46. This action will be seen to draw the belt moretightly into the V-groove 44 about the knee joint cylinder 41, so as toprevent rotation thereof with respect to the side plates of the lowerleg portion. Similarly, pivoting of the foot in the opposite directionwill produce a relatively upward movement of the activator 62, so thatagain the cam actuator 53 is urged to rotate in a clockwise directionand produce the same results. It will thus be seen that for eitherdirection of rotation of the foot about the ankle joint, the cam 47 iscaused to rotate to tighten the belt at the knee joint and lock the kneeagainst rotation. While this action is highly advantageous andconsidered to be a marked improvement in the art, the present inventionincorporates further improvements as described below.

In addition to the connection of activators 61 and 62 to the activatorpin 81 secured between actuator arms 54 and 54', there is also provideda sleeve 82, pivotally mounted upon the activator pin 81 and extendingupward therefrom with a plunger 83 slideably disposed therein. The upperend of this plunger 83 is flanged and a compression spring 84 isdisposed between such flange and the upper end of the sleeve 82. In theillustrated embodiment, this sleeve and the plunger are approximatelymidway between the side plates 32, 32' and the plunger 83 is pivotallyconnected at the upper end thereof to a depressor 86 which may havesomewhat of an inverted T configuration in side elevation and aninverted forked configuration in end elevation. The pivotal connectionis accomplished by a depressor pin 87 extending between the sides of thedepressor and through a bore in the top of the plunger 83. The depressoris also connected in rotatable relation to the roller 48, as byextension of the ends thereof through the sides of the depressor, sothat the depressor is actually pivotal about the roller axis by means ofthe plunger 83. The upwardly ending portion of the depressor 86 includesa head 88 aligned with the V-belt 46 immediately adjacent the cylinder41 and preferably slightly below the center thereof. This head 88 isadapted to be pivoted against the belt to depress the belt further intothe groove 44 in the cylinder to initiate a binding action wherebypivoting of the cam 47 will not slide the belt about the cylinder, but,instead, will further urge the belt into the V-groove about the cylinderand, consequently produce a locking action between belt and cylinder.

There are also provided a pair of retractor springs 91-92 which arestretched between the activator pin 81 and the side plates 32-32,respectively, below the cam shaft. These springs pull the activator pin81 downwardly so as to resist cam tightening and also angle jointpivoting.

In addition to the elements previously described, there are furtherprovided herein certain physical stops which are either requisite ordesirable for completely safe operation of the present invention. Thus,first considering the ankle joint, there is noted to be illustrated inFIG- U-RE 1 a stop 101 in the form of a fixed boss extending from anankle plate 29 in front of the side plate 32. Pivoting of the anklejoint is thus limited in movement to the point of contact between theside plate 32' and the stop 101 and this may be made adjustable by theprovision of a set screw '102 threaded into the leading edge of the sideplate 32' and having a lock nut thereon. In practice, a maximum degreeof rotation is normally limited at the ankle joint to about 6'. Physicalstops are also provided at the connection of activators and cam actuatorwherein it will be seen that movement of one activator upwardly, uponpivoting at the ankle joint, will cause the other activator to movedownwardly. As either activator moves downwardly, it will slide alongthe activator pin through the slot 69 until the set screw 71 engagesthis pin. This, then, limits the total rotational movement available atthe ankle joint. This latter stop mechanism is applicable to ankle-jointpivoting in either forward or backward direction, and the purpose of theadditional stop 101, for pivoting in the forward direction, is discussedbelow. At the knee joint there are also provided certain physical stopsto prevent rotation of the knee joint past vertical in one direction andmore than about in the opposite direction. The first of these stops maybe best seen in FIGURES 1 and 2, and as shown in FIGURE 1, there isprovided upon the end plate 42 a small boss 106 in position to contactthe sideplate 32 when the upperand lower-leg portion are in verticalalignment.

Adjustment of the stop may be accomplished by the provision of a smallset screw 107 threaded into the leading edge of the side plate 32 andhaving a lock nut thereon to fix the position of the screw aligned withthe boss 106. Limitation upon opposite rotation of the knee joint isprovided by a pair of pivotally mounted spring-loaded pawls 111 and 111mounted for rotation on the shaft of roller 48 to ride on the rearundersurface of the cylinder 41 and adapted to engage small bosses 112,112 extending radially therefrom. These pawls 111 may be operated fromlongitudinally adjustable arms 113, 113' pivotally mounted at theirlower ends upon the activator pin 81 and carrying at the upper end leafsprings 114, 114' secured to the back side of the pawls 111. This, then,provides for pivoting of the pawls 111 upwardly against the cylinder 41when the knee joint is pivoted and weight applied to the leg so that theangle joint pivots. The latter stops, including the pawls 111 and 111,are only added for precautionary measure and in most instances may beexcluded from the structure.

Considering now operation of the present invention, as described above,and referring again to the drawings, it is first noted that theartificial limb of the present invention is adapted for connection tothe upper leg of an amputee or a person having a leg missing, so as tosimulate a real leg, for the purposes of walking and the like. Some typeof upper connection, forming no part of the present invention, isaffixed to the leg stump with the present invention depending therefrom.In clear distinction from conventional, artificial legs, the presentinvention provides for locking of the knee joint in accordance withmovement of the ankle joint. It will be appreciated that in the presenceof a downward pressure on the leg any forward shifting of the weightatop the leg will cause the ankle joint to pivot, inasmuch as theunderside of the foot is presumably resting on some fixed surface. Thispivoting of the angle joint occurs by a forward movement of the upperportion of the invention so that effectively the side plates 32, 32swing to the right in FIGURE 1. The activators 61 and 62 are freelyrotatable about anchor pins 67 and 67 at the ankle so that theactivators also swing forwardly at their upper ends. This, then, appliesan upward force upon the activator pin 81 of FIGURES 3 and 4 to rotatethe cam 47 through the cam actuator 53. As the eccentric cam surface 49is rotated in the clockwise direction, in this case by the activator 61,it applies a force to the belt. At the same time as the cam actuator 53is rotated by the activator 61, the piston 83 is moving upwardly by thesleeve 82 pushing the upper piston flange through the compression spring84. This, then, causes the depressor 86 to rotate about the roller shaft48 and press with the presser head 88 against the V-belt. With the notedlocation of the depressor head 88 against the V-belt behind the cylinderand immediately below the center thereof, this belt is initially pushedfurther into the groove about the cylinder so that the cam movementcauses the belt to tighten into the groove 44 about the cylinder 41. Thedepressor 86 thus prevents creeping of the belt about the cylinder. Itwill, of course, be appreciated that alternative means may be providedto prevent such possible creasing as, for example, by fixing the beltbetween a cam and a fixed point such as a bar between the side plates.In such a situation, the depressor and associated elements may beomitted; however, there then should be provided a compresison spring inthe activator 61 or 62 if the spring 84 is omitted.

Further to operation of the depressor 86, it is noted that upwardmovement of the activator pin 81 applies a force to the depressor forrotating it about the roller shaft 48 through the compression spring 84.Following application of a sufficient force to the V-belt by thedepressor head, additional upward movement of the activator pin 81merely serves to compress the spring 84 so that this spring does then,in eifect, accommodate overthrust. Although the V-belt locks the kneejoint, the ankle joint is yet free to pivot further forwardly until thestop 101 is engaged by the side plate 32 or the adjusting screw 102thereon. Appropriate adjustments are made, both by this adjusting screw102 and the set screw 71' at the upper end of the activator 62, so bothstops come into effect at the same time. As previously noted, upwardmovement of the activator 61 results in a corresponding downwardmovement of the activator 62 so that the latter slides downwardly on theactivator pin 81 until the screw 71' engages this pin. Inasmuch asnormal operation of an artificial leg moves body weight forwardly of thefoot, it is desirable to provide a positive stop 101 in this direction.Insofar as opposite rotation of the ankle joint is concerned, the setscrew 71 atop the activator 61 is sufficient, for in this direction bodyweight is shifted over the heel and consequently, lesser forces areapplied on the activator 61 when it serves as a stop.

Upon removal of weight from the artificial leg hereof, the ankle jointis freed to pivot back into normal position as illustrated in FIGURE 1and the springs 91, 92 do then swing the angle joint back into thisposition. As the ankle joint swings into normal, horizontal position,the cam 47 is rotated to free the V-belt 46 and consequently unlock theknee joint so the lower leg 22 may be swung forwardly much in the mannerof a pendulum, by swinging the upper leg. In order to prevent overshootwherein the knee joint may pivot the lower leg beyond alignment with theupper leg, the stop 106 is provided. There may thus be accomplished withthe artificial leg of the present invention, a substantially normalwalking action. In particular it is noted that whatever the rotationalor pivotal position of the knee joint may be, a downward pressure uponthe knee joint transmitted through the artificial leg to a fixed surfacebeneath the foot, will result in a pivoting of the ankle joint so as tolock the knee joint. This, then, positively prevents any possiblecollapse or free swinging of the knee joint when weight is appliedthereto. This foregoing point is believed to be apparent insofar as thestanding position is concerned. It is, of course, physically possible topress downwardly upon the artificial limb with the foot flat against afioor or the like without moving the ankle joint to lock the knee joint.However, as soon as weight is shifted from vertical, the ankle jointdoes pivot and a locking action occurs at the knee joint so that as theweight is progressively shifted the locking action becomes greater andno collapse of the knee joint is possible.

In usage, the present invention is found to closely simulate actual legaction in many respects. In particular it is noted that a cushioningeffect is provided so that the user feels somewhat as though he iswalking on a carpeted floor. Also the user is reassured upon realizationthat the knee joint cannot collapse or pivot free at any time that hehas his weight placed thereon and consequently he is in no danger offalling despite stumbling or missteps. Common occurrences such asstubbing ones toe, with the present invention results in the applicationof body weight to the leg with the knee joint bent and this will be seento immediately lock the joint so that weight can be applied downwardlythrough the artifical leg so that the wearer can hold himself up withthat leg to regain his balance.

What is claimed is:

1. A prosthetic device composing an artificial foot, a lower leg, meansdefining a rotatable ankle joint connecting said lower leg and foot,means defining a rotatable knee joint having connecting means atop samefor joinder with an upper leg and including a rotatable cylinder havinga circumferential groove therein, a belt disposed in said groove, arotatably mounted eccentric cam engaging said belt for tightening samein said groove upon cam pivoting, spring means urging said cam into anunpivoted position, and a pair of activators extending from said foot tosaid cam with one being pivotally mounted ahead of the ankle joint andone behind the ankle joint whereby pivoting of the foot about the anklejoint in either direction pivots the cam through said activators totighten said belt and lock the knee joint.

2. A prosthetic device as set forth in claim 1 further defined by meansengaging said belt and urging same into said groove at least at thecommencement of cam pivoting for preventing creeping of the belt aboutthe cylinder upon cam pivoting.

3. A prosthetic device as set forth in claim 2 further defined by themeans engaging said belt comprising a pivotally mounted depressor havinga portion aligned with the cylinder groove adjacent said belt for urgingthe belt tightly into the groove at the commencement of cam pivoting,and means connecting said activators to said depressor for pivotingsame.

4. A prosthetic device as set forth in claim 1 further defined by saidlower leg comprising a pair of elongated rigid side plates extendingbetween ankle and knee joints, said ankle joint comprising a pair ofupstanding walls on said foot with an ankle shaft therebetween andextending in rotatable relation through said side plates, and said kneejoint comprising said cylinder disposed between said side platestransversely of the leg with at least one shaft rotatably mounting saidcylinder between said side plates.

5. A prosthetic device as set forth in claim 4 further defined by a camshaft extending through said cam between said side plates for rotatablymounting said cam, a cam actuator rotatably mounted on said cam shaftand having a movable portion engaging said cam for adjusting the initialposition thereof and a pair of actuator arms extending from said shaftwith a depressor pin therebetween, said activators each having alongitudinal slot of adjustable length adjacent the top thereof throughwhich said depressor pin extends.

6. A prosthetic device as set forth in claim 5 further defined by asleeve pivotally carried by said depressor pin and having a plungerprovided with a flange and slideably disposed therein with a compressionspring disposed about said plunger between the top of said sleeve andthe plunger flange, and a shaft pivotally connecting said depressor andplunger for pivoting of the depressor through the spring.

7. A prosthetic device as set forth in claim 6 further defined by thespring means of claim 1 comprising a pair of restoring springs connectedbetween said depressor pin and the side plates below the cam for pullingthe depressor pin down to urge the foot into horizontal position throughsaid activators.

8. A prosthetic device as set forth in claim 4 further defined by a bossupon one of the upstanding walls on said foot ahead of the side plateadjacent said wall in position to engage said plate upon limitedpivoting of the ankle joint, and means threaded upon said latter sideplate for extension toward said boss to adjust the maximum allowableankle joint pivoting.

9. A prosthetic device as set forth in claim 1 further defined by afirst stop comprising a spring-loaded pawl pivotally mounted adjacentsaid knee-joint cylinder for riding thereon and a radial projection onsaid cylinder disposed to engage said pawl upon predetermined kneejointpivoting from vertical, and a second stop including a boss upon an endof said cylinder for engaging the front of a side plate when the latteris substantially vertical and means for adjusting the location of saidside-plate front adjacent said boss to establish maximum knee-jointpivoting forwardly.

10. A prosthetic device as set forth in claim 1 further defined by saidbelt being endless and extending about both cylinder and cam, and bothsaid cylinder groove and belting having a V-shape in cross section formaximized gripping of the cylinder by the belt upon cam pivoting.

References Cited UNITED STATES PATENTS 21,289 8/1858 Wilcox 3-23 XR762,031 6/1904 Engels 327 10 9/ 1928 Neumann 323 5/1951 Havens 32711/1951 Fischer et al. 32

2/1960 Chiasson 3--27 FOREIGN PATENTS 9/ 1951 Austria.

1/ 1922 Germany. 7/ 1957 Great Britain. 11/1954 Italy.

US. Cl. X.R.

